Abstract: A formal verification tool that verifies multiple sequentially-generated versions of a core circuit design by obtaining search path information from the formal verification solver for each property that is proven or disproven during a first formal verification session involving an earlier-generated circuit design version, and utilizing the search path information to perform search-path verification processes during a subsequent formal verification session to quickly verify the proven/disproven properties in a later-generated circuit design version. Each property's search path information includes counterexample traces or proof artifacts identifying the search operations utilized to achieve a corresponding counterexample or proof object that proves/disproves the property. Search-path verification involves applying the stored search path information to the later-generated circuit design version, and determining if the same counterexample or proof object is achieved.

Abstract: Relates to automatic conversion of assumption constraints, used in circuit design verification, that model an environment for testing a DUT/DUV, where the assumptions specify sequential behavior. Such assumptions are converted, with the use of logic synthesis tools, into a gate-level representation. For formal verification, a verification output is constructed from the gate-level representation and DUT/DUV assertion-monitoring circuitry. A formal verifier seeks to prove the verification output cannot indicate a design error. For simulation verification, the gate-level representation is converted into a hybrid representation comprising pipelines and combinational constraints. During simulation, the pipelines hold state information necessary for a solution, of the combinational constraints, to be in accord with the sequential assumption constraints. For certain sequential assumption constraints, the combinational constraints are insufficient to insure avoidance of deadend states.